Corrosion inhibitor composition



The present invention relates to inhibition of corrosion and more particularly it is concerned with new and useful compositions which may be employed in acid solutions to decrease the corrosion of metal in contact with the acid solutions.

Prior known compositions for the inhibition of corrosion of metal surfaces have in many instances employed relativel expensive chemicals. Additionally many of the most effective chemicals are unusually diflicult to handle. Further, while the percent reduction in corrosion is relatively high, there is still much room for improvement to increase efliciency and safety.

It is an object of the present invention to provide a new and useful composition which substantially inhibits the solubilization (corrosion) of metals in contact with corrosive acids. It is a further object of the present invention to provide a composition for the inhibition of corro sion of metal surfaces in contact with corrosive acids which is relatively inexpensive and easily handled. An additional object of the present invention is to provide an improved corrosion inhibitor composition which is useful with aqueous mineral acids. These and other objects will become apparent from the following specification and claims directed to those skilled in the art.

It has now been found that a synergistic corrosion inhibition can be obtained by employing as the inhibitor a mixture of an amine and an acetylenic alcohol having the formula wherein each R represents hydrogen, 'loweralkyl, phenyl, substituted phenyl or hydroxyalkyl radical and the a Rs may be joined together to form a cyclohexyl ring. The activity of the amine and acetylenic compound is effectively synergized when the amine is employed in amounts of from 10 percent to 90 percent by. volume of the inhibitor composition. Good results are obtained when the inhibitor composition( the amine-acetylenic mixture) is .employed in aqueous acid solutions in concentrations of from 0.05 to 1.0 percent by volume.

Various acetylenic alcohols and diols when associated with various amines and employed in accordance with the present invention are found to exhibit with the amine a synergistic effect. Thus, for example, propargyl alcohol, 1,4 butynediol, ethynylcyclohexanol 3-methyl-1- nonyn-3 ol, 2 methyl-3-butyn-2-ol, a'ethynyl-2,4,'6-trimethyl-benzyl alcohol, 2-methyl-l-pentyn-3-ol, ot-ethynylbenzyl alcohol and the like when employed in accordance with the present invention exhibit the synergistic anticorrosion effect.

Similarly, various amines when employed in accordance with the present invention with the acetylenic alcohols exhibit a synergistic effect. Thus, for example, one can employ pyridine, alkylpyridines or mixtures thereof, the primary, secondary or tertiary aliphatic amines, such as, butylamine, dibutylamine, tributylamine, amylamine diamylamine, triamylamine and the like. The alkyl amines which have been found most effective are those havingfrom' 4 to 10 carbon atoms in each alkyl sub- 3,107,221 Patented Oct. 15, 1963 stituent. The heterocyclic amines which have been found to provide good results are the alkylpyri'dines, such as those commerciallyknown as alkylpyridines HB, a mixture of alkylated pyridines having an average molecular weight of 170.

In carrying out the present invention the corrosion inhibitor is mixedwith an aqueous solution of a mineral acid or with water which is thereafter mixed with the mineral acid. The inhibited acid solution may then be employed in oil-well 'acidizing or industrial acid-cleaning.

In a preferred manner of carrying out the present invention, the alkylpyridine and the acetylenic compound are mixed together, in the range of ratios herein before described, as an aqueous mixture, preferably with a surface-active agent. The resulting mixture is agitated to assure complete distribution of the additives in the aqueous phase. Thereafter, the desired mineral acid is mixed with this aqueous mixture to obtain inhibited acid suitable for use in oil-well aeidizing or industrial acid-clean ing.

. Various acids, particularly the mineral acids, have been I found to be effectively inhibited against metal corrosion by the employment of the compositions of the present invention. Thus, sulfuric, phosphoric, acetic and hydrochloric acids and the like may be effectively inhibited when employing an acetylenic alcohol or diol in combination with an alkylpyridine.

The inhibitors of the present invention are operable when employed at temperatures as high as about 275 F. About this temperature, while some inhibition is found to exist, the corrosion rate is above that which is permissible in field operations both economically and safetywise.

The following examples illustrate the present invention but are not to be construed as limiting.

Example 1 561 gallons of water, placed in a 1,000 gallon tank provided with an air lance was mixed with 1 gallon of the product obtained by the condensation of di-sec-butylphenol with 10 moles of ethylene oxide, 2 gallons of alkylpyridines I-IB (a mixture of high-boiling alkylpyridines with an equivalent weight of approximately 170,

obtained from Carbide and Carbon Chemicals Company) and 2 gallons of propargyl alcohol. The resulting mixture was agitated with the aid of an air lance for approximately 15 minutes. Thereafter, continuing the agitation, 434 gallons of 32 percent hydrochloric acid was added to the mixture. The resulting mixture, 1000 gallons, was an inhibited 1-5 percent hydrochloric acid solution which was useful as an oil-well acidizing solution.

Examples 2-16 Various inhibitor compositions were prepared from an alkylpyridine and an acetylenic alcohol or diol and employed to inhibit 15 percent hydrochloric acid. Corro-' sion tests were run at F. for 16 hours. The test metal was AISI 1010 and mild steel compound 2% inches Various types of surface-active agents have been found I A 4 wall thickness of 0.187 inch). are tabulated below:

1 inch by 0.12 inch. The results of such tests are The results of such tests ulated in the table below.

r. Corrosion Ex. Corrosion J Concentration inhibitor (percent by volume) rate No Concentration inhibitor (percent by volume) rate (ibs/ftJ/day) (lbs/ftJ/(iay) 0.4 percent alkylpyridines 11B (coded 11B) 0. 070 31... 0.5 percent propnrgyi nlwhol 0.415 0.4percent1,4-lmtyncdioi (coded l11)) 0.037 32... 0.5 percent aikylpyridines ill! 0.506 0.4 percent etllynyleyclohexnnoi (coded LCll) 0.1 4 3.5... 0.5 percent mixture 1 port by volume nlkylpyri- 0.1 percent propargyl alcohol (coded PA) 0.031 dines llli plus 1 port propargyi alcohol 0.110 0.41 pertelnt milxturenttlgparts by volume 1113 plus 0.0003 2;.--

fi lflh mgidigg.. gu h 0.158 par yvo ume r ure 0 i o yyr ne 0.4 percent mixture (7 ports 11B plus3 parts BD)- 0. 0064 plus 1 part proparizyl alcohol 0. 061 0.4 percent mixture (5 parts 111; plus 5 parts BD).. 0. 0074 30. 1.0 percent 2-:nnine-2-etl1yl-1,3-prop1medl0l. 0. 583 0.4 percent m xture (3 parts 111% plus7 pnrts13l)) 0. 0004 37.-- 1.0 percent mixture 1 part 2-amlno-2-ethyl1,3- 0.4 percent m xture (1 part 1111 plus 9 parts BD). 0.014 propnnediol plus 1 port propargyl olcohoL 0.196 .n 0.4 percent mixture (9 parts 118 plus 1 port 11011). 0. 0036 33.-- 1.0 percent di-iso-nmyiamine 0. 291 0.4 percent mixture (7 parts 118 plus3 parts E011). 0.0008 39.-. 1.0 percent mixture 1 part di-isoamyiam1ne plus 0.4 percent mixture (5 parts 110 plus 5 parts ECU)- 0.0015 3 1 port proparcyl alcohol 0. 0-18 0.4 percent mixture (3 parts 1115 plus? parts ECIIL 0. 0012 40... 1.0 percent'tri-n-amyhnninc 0.231 0.4 percent mixture (1 part 1113 plus 0 parts E011). 0.0013 41... 1.0 percent mixture 1 port tri-n-umylomine plus 1 0.12160 mixture (5 parts 1111 plus 5 parts PA) 0.013 port propargyi alcohol 0.021

Exam [as 41-56 Examples 17-22 20 E l s p h d hl d mp oymg aqueous percent y me one act ing surface'lactfve i t gygf deter hibited with a composition of the present invention and me In g gnanner owlng t e {E ais a a standard commercial inhibitor, AW (a corrosion in- P t) y fl al F hi-bitor employed in the acidizing of oil wells), tests were a g i i 1 partf "139 gg j run employing various metals to determine the effective- 3 an y o z ig ness of the anti-corrosion properties on these metals. The as run at a temperature 0 or ours' e corrosion rate of the metals after a 6-hour immersion in st metal was AISI 1010 mild steel. The results of the the inhibited acid are shown below nployment of various types of surfactants is tabulated i the following table. 30

Ex. Corrosion N0. Metal Cone. inhibitor( ercent 'Iem rate (lbs/1L Fix. Concentration of surface active agent Ionic Corrosion by volume F. day) do. added (percent by volume) activity (lb llfigtgd s. ay

.3 percent formulation 150 0.163 .25 percent A30W- 150 0. 465 None 0.016 .3 percent tormulutio 175 0. 0081 0.1 percent di-sec-butylphcnol eon- Nonion1c 0.013 .25 percent A30W..- 175 0.022 delndsed with 10 moles ethylene percent forkrgnuvlc stion 175 0. 023 ex 0. percen 75 0.023 0.1 pirlcelrt nolnylrglfierliol eon dlensed do 0.015 og5percenttfrzrmulatit; 175 0.0025 W1 1 mo use yenc ex 0. perccn ormu at 011 175 0.0033 O.lbpercent ammorriium isopropyl- Anionic"- 0.015 perccnt ftoarglgtion 175 0. 0017 enzcne-para-su onate. o percen 75 0. 0050 0.1 percerit dioetyl sodium sulfodo.. 0.000 gg percent fojrxriaili ltion succlna e. a pcreen r 0.1 percent 1 trilmcthylstcaryl-am- Cationic 0.014 Adnairalty. U.3[)0l0(311i.0l1\fl6li 1tl0n 1;; 0.0012 monium ch ori e. 0.25 percen 1 0.0013 0.3rwrcentforn1ulotion 175 0.0019 0.25 percent A30W 175 0.0015

Examples 23-29 Varied concentrations of the inhibitor mixture of the resent invention were employed to determine the effect I Formulation composed of 2 parts by volume nlkylpyridines 1111 plus 2 parts progargyl alcohol plus 1 part di-scc-butylphenol condensed with 10 moles et ylene oxide.

1 concentration of the inhibitor in hydrochloric acid. Examples 57 63 he inhibitor consisted of a mixture 2 parts of alkylyridine, 2 parts by volume of propargyl alcohol and 1 Employms vanous P -f ,tesis were T to determme art of the condensation product of di sec butylphenol the effectiveness of'the inhibitor compositions at 150 F. with 10 moles of ethylene oxide. The test was run emand 16 hours f AISI 1010 smelt the following loying AISI 1010 mild steel coupons at 150 F. for 16 results we're obtamed' ours. The results of the test employing various concenrations of inhibitor in a 15 percent hydrochloric acid Inhibitor concentration Corrosion olut on are tabulated below, No Acid media (percent by volume) ratolbsilftfll Corrosion Co c o inhibitor (pe c y o me spmentsulmflcou None M3 (lbsJftJ/day) 60 58--. 0. 4 percent formulation A 0.070 3% 5 t 4 percent formulation B 0. 0.4percentalky1pyridines HB 0.076 phosphoric. 'gfgsggg ggggg g 8' 8 2 61- o 0. 4 percent formulation B g. 3%; 5 33:33? 22332 2x232? 0.4 percent formulation B 0.006 g fispercenttabgve 222211mitriue 0. 0026 Force a We X l Formulation A-2 parts by volume propargyl alcohol plus 2 parts percent above mum) 0024 alkylpyriilines 1113 plus 1 part di-sce-butylphenoi condensed with 10 moles ethylene oxide.

' Formulation 13-1 port by volume cthynylcyelohexnnol plus 1 part Examples 314 alkylpyrldincsllll. The following tests were run to determine the syner- We claim: istic effect of various amines. 15 percent hydrochloric 1. A metal corrosion inhibitor for use with aqueous tcid heated to 200 F. and containin one of the inhibitor acids which com rises an amine selected from the t rou g P. g :ompositrons listed below was employed to determine the consisting of pyridine, lower alkyl pyrrdmes, alkylanunes affect of the inhibitor on API N80 tubin linch uarterhaving from 4 to 10 carbon atoms, inclusive, in each iegment of 2.375 inch outside diameter tubing having a alkyl substituent, and hydroxy lower alkylarnines, and an acetylenic alcohol having a formula selected from the group consisting of R R cEc- 1oII and and

wherein each R represents a member of the group consisting of hydrogen, lower alkyl, phenyl, alkyl substituted phenyl and hydroxy alkyl radicals having from 1 to 4 carbons, inclusive, from 1 to 9 parts by volume of an amine compound selected from the group consisting of pyridine,

lower alkyl pyridines, alkylamines having from 4 to 10 carbon atoms, inclusive, in each alkyl substituent, and, hydroxy lower alkylamines, and, from 0 to 2 percent by volume of a surface-active agent stable in aqueous acid.

3. A corrosion-inhibited mineral acid comprising an aqueous solution of mineral acid containing (1) from 0.05 to 1.0 percent by volume of a mixture consisting of from 9 to 1 parts by volume of propargyl alcohol and from 1 to 9 parts by volume of a mixture of alkylpyridines having an average molecular weight of 170, and (2) from 0 to 2 percent by volume of a surface-active agent stable in aqueous acid.

4. A corrosion-inhibited mineral acid comprising an aqueous solution of mineral acid containing (a) from 0.05 to 1.0 percent by volume of a mixture consisting of from 9 to 1 parts by volume of propar-gyl alcohol and from 1 to 9 parts by volume of alkylamine having from 4 to 10 carbon atoms, inclusive, in each alkyl substituent, and (b) from 0 to 2 percent by volume of a surface-active agent stable in aqueous acid.

5. A corrosion inhibited aqueous hydrochloric acid solution consisting essentially of about 15% by weight of HCl inhibited against corrosion by the addition thereto of a corrosion inhibiting amount of a composition consisting of equal parts by volume of propargyl alcohol and a mixture of high boiling alkyl pyridines having an equiva lent weight of about 170.

References Cited in the file of this patent UNITED STATES PATENTS 2,053,024 Dreyfus Sept. 1, 1936 2,472,400 Bond June 7, 1949 2,688,368 Rodgers et al. Sept. 7, 1954 2,814,593 Beiswanger et al Nov. 26, 1957 2,846,295 Patterson et al. Aug. 5, 1958 2,913,408 Pumpelly et a1. Nov. 17, 1959 OTHER REFERENCES Ito: Tar Base as Corrosion Inhibitor, article in Chemical Abstracts, vol. 50, 1956, pp. 16632 and 16633. 

1. A METAL CORROSION INHIBITOR FOR USE WITH AQUEOUS ACIDS WHICH COMPRISES AN AMINE SELECTED FROM THE GROUP CONSISTING OF PYRIDINE, LOWER ALKYL PYRIDINES, ALKYLAMINES HAVING FROM 4 TO 10 CARBON ATOMS, INCLUSIVE, IN EACH ALKYL SUBSTITUENT, AND HYDROXY LOER ALKYLAMINES, AND AN ACETYLENIC ALCOHOL HAVING A FORMULA SELECTED FROM THE GROUP CONSISTING OF 